1. Field of the Invention
This invention relates to a method for recording binary data on a piece of material such as a card and to a printed body where data are recorded by the method.
2. Description of the Prior Art
Heretofore, a bar code system is employed for displaying binary data on a piece of material.
In this system, data are recorded by arranging a group of variously patterned black bars and spaces. The recorded data are read out in such a manner that a light beam emitted from a reading device is scanned in the direction of a series of adjacent stripes, light reflected on a piece of material where the bars are printed is successively detected, and it is transferred into electric signals.
Nowadays, a great deal of data have come to be recorded in such a bar code. This, however, caused a problem that the reading device might read out data by mistake because of a long series of bars. Further, there is a problem that it is difficult to accurately arrange spaces between black bars composing a bar code.
To record such data more simply, another method for recording data is proposed wherein there are formed a first bit indicating field for displaying the first bit of a binary number, a second bit indicating field for displaying the second bit thereof, a third bit indicating field for displaying the third bit thereof, and a fourth bit indicating field for displaying the fourth bit thereof, the first through fourth bit indicating fields are individually marked to produce a code mark as a unit displaying binary data, and the code mark is printed on a piece of material (see Japanese Patent Application Early Laid-open Publication No. Sho 63-132093).
According to the previously proposed method, the cardinal number 1001 in the binary system (equivalent to 9 in the decimal system) is recorded by painting out the first and fourth bit indicating fields, for example.
However, when quite a lot of various data are recorded, such a code mark type of method still has several disadvantages such as arrangement of a plurality of code marks, lack of the concealment of data, or insufficient prevention against forgeries although the record of data has come to be easily carried out than before.
To overcome those problems, the present invention aims to provide a method for recording data for recording a lot of data in a code mark; a data recording medium wherein recorded data are hard to fade out, they are tightly concealed, and forgery is not easily committed; and a method for reading data, as well as a method for dissolving the difficulty in record of data.